a) X x 2,8 + X x 5,2 = 48
X x (2,8+5,2)=48
X x 8=48
X=48:8
X=6
b) X x 12,6 - X x 5,6 =42
X x (12,6-5,6)=42
X x 7=42
X=42:7
X=6
Các câu khác làm tương tự nha
a) x * 2.8 + x * 5.2 = 48
<=> x * ( 2.8 + 5.2 ) = 48
x * 8 = 48
x = 48 : 8
x = 6
b) x * 12.6 - x * 5.6 = 42
<=> x * ( 12.6 - 5.6 ) = 42
x * 7 = 42
x = 42 : 7
x = 6
c) x * 12.25 - x + x * 2.75 = 1050
<=> x * ( 12.25 - 1 + 2.75 ) = 1050
x * 14 = 1050
x = 1050 : 14
x = 75
d) x * 9.1 + x * 1.9 = 26.4
<=> x * ( 9.1 +1.9 ) = 26.4
x * 11 = 26.4
x = 26.4 : 11
x = 2.4